Polyvinyl alcohol nanofibers reinforced with polybenzimidazole: Facile preparation and properties of an anion exchange membrane

Abstract

The search of novel materials for anion exchange membranes (AEMs) is a key factor in addressing challenges of electrochemical energy conversion and storage devices in terms of cost, durability, efficiency, and up‐scalability; and composite materials based in electrospun nanofibers have a great potential in this regard. We report a facile preparation method of an AEM composed by polyvinyl alcohol (PVA) nanofibers crosslinked with glutaraldehyde (GA) and reinforced with poly[2‐2′‐(m‐phenylene)‐5‐5′‐bibenzimidazole] (ABPBI) polymer, characterizing it as an AEM in a liquid alkaline water electrolyzer (LAWE) device. Homogeneous and flexible membranes were obtained, with a good chemical stability in the doping solution (15 wt.% KOH), and better swelling resistance than pure ABPBI membranes. The membranes also showed a specific ionic conductivity of 36 mS·cm−1 at 60°C and 41 mS·cm−1 at 80°C, with an activation energy value of 3.5 kJ·mol−1. Regarding LAWE performances, it attained current densities of 236 and 271 mA·cm−2 for a 2 V cell voltage when operated at 50°C and 70°C, respectively. During chronopotentiometric test, neither potential drop nor change in material integrity were observed. These results provide a facile and scalable method for low cost AEMs preparation, contributing as an alternative material for its use in electrolyzers.

Recent progress in anion exchange membranes (AEMs) in water electrolysis: synthesis, physio-chemical analysis, properties, and applications

“…Recently, PVA was crosslinked with ABPBI (e.g., C-PVAf-ABPBI) polymer using glutaraldehyde (43 mS cm −1 ). 131 This composite material performed better in IC than bare PVA crosslinked with glutaraldehyde (28 mS cm −1 ) and PVA crosslinked with ABPBI ber (36 mS cm −1 ) at 60 °C. The higher IC of the composite membrane may be attributable to the separation of hydrophilic and hydrophobic molecules in a well-ordered manner to increase the conductivity of the membrane.…”

“…Coppola et al improved the WU of an ABPBI with a PVA. 131 As a result, the membrane ABPBI only exhibited 48.0% and was increased by 67.0% aer compositing with PVA. Due to the PVA's hydrophilic properties, which allow it to absorb more water into the membrane, its WU was higher.…”

“…Researchers have synthesized a composite of PVA nanobers crosslinked with glutaraldehyde (GA) and poly[2-20-(mphenylene)-5-50-bibenzimidazole] (ABPBI) AEMs (PVAf/ ABPBI). 131 Initially, PVA nanobers prepared by electrospinning were crosslinked with GA. Aerward, the cross-linked PVA membrane was composited with ABPBI polymer by immersing the lm in dissolved ABPBI solution under a reux method. Later, the membrane was soaked in 3.1 M KOH to form OH − ions for 7 days, longer than other membrane processes for ion formation.…”

“…Coppola et al investigated AS on the ber form of a PVA-crosslinked ABPBI membrane (C-PVAf-ABPBI) in a 15% KOH solution at 30 °C and found that the membrane was more stable than bare PVA ber or glutaraldehyde crosslinked PVA for up to 7 days. 131 The ABPBI membrane may thereby improve the membrane's stability in an alkaline setting. Yang et al investigated AS for VImPPO:PVA semiinterpenetrated polymer networks sIPN-91) in 1 M NaOH at 80 °C.…”

Structures and properties of polymers in ion exchange membranes for hydrogen generation by water electrolysis

“…Hence, this type of low-cost PISPVA-based AEMs can be used for the electrolysis of low concentration alkali solution or pure water. Coppola et al59 recently reported low-cost AEMs that were prepared from glutaraldehyde crosslinked nanofibrous PVA (GA-c-PVANF) and poly[2-2 0 -(m-phenylene)-5-5 0bibenzimidazole] (ABPBI). This GA-c-PVANF/ABPBI-reinforced nanocomposite membrane exhibited ionic conductivity values of 36 and 41 mSÁcm À1 at 60 and 80 C, respectively.…”